How hot of water can bluegill tolerate?

[Jon Easterling]

I am in Texas and its hot.

[Jay Wolf]

TCLynx probably has a better answer than me but this is what I know.  Obviously (depending on the strain of bluegill) you want to grow them as fast as possible.  In Minnesota, 72 degrees is optimal temp. to grow them really fast.  I am sure they could tolerate temps as high as 85 degrees, but then you have to worry about oxygen levels and stressing the fish.  I hope this helps at least a little.......

[TCLynx]

Well so far I know my blue gill have survived water temps over 90 F in my 300 gallon system.  Unfortunately the wireless temp sensor quit working for a period of time and so I lost like the last month and a half of min/max temp readings on the data logger so I can't tell you how far over 90 F they have survived.

I can tell you that you need extra supplemental aeration when the water temp is staying above 80 F most of the time as the fish went off the feed without it when the night time water temps were not dropping into the lower 70's anymore.

 

Anyway, I think if you have at least 300 gallons of fish tank and provide shade over the fish tank and a little bit of shade over the plant beds through the worst heat of the day/summer then you can probably keep the fish from cooking, especially in a dry climate where you might get some evaporation cooling and more cooling off overnight.  Here in FL, with the humidity it is hard to get the cooling overnight in summer but when the rains come it helps some.

 

I would say ease off the feed a little bit as the water temps are up over 86 F and if the water is getting consistently over 90 F you will need to reduce feed a bit more and if getting over 95 F I would probably switch the system over to constant flood  to reduce the heating of the water in the flood and drain grow beds and get more water mass into the system to moderate the temperatures even more.  Water over 95 F I would probably not be feeding much at all due to the reduce dissolved oxygen holding capacity of the water and if the water is nearing 100 F I would probably be cycling frozen water jugs into the system.

 

Luckily I don't think I've every had the water in my larger systems get over 95 F and that was only the water being pumped out of the monster grow bed before it was shaded by plants.  Small systems will have far more trouble with heat and cold.

[Jim Logios]

I have a small system (Aquabundance 60 gallon) in a greenhouse. I am in central VA, and it gets very hot and humid here.  It's been 95 and above for the last two weeks straight. By covering my greenhouse with shadecloth, and shielding the light off the ft, the temps have not gotten over 86.  I was very worried about this when I first started, before I got the shade cloth, and when I was fishless cycling, the water was getting over 102-105 daily. Shielding your ft with shadecloth will certainly keep the temps down.  I have yet to face cold temps... guess that will be another adventure to experience!

TCLynx said:

Luckily I don't think I've every had the water in my larger systems get over 95 F and that was only the water being pumped out of the monster grow bed before it was shaded by plants.  Small systems will have far more trouble with heat and cold.

[TCLynx]

Good to hear your success in keeping your greenhouse cool through summer!

[Linda Sunshine Haynie]

An idea you might want to try for controlling hot water.  My Husband is in the HVAC (air conditioning) field.  He explained to me that air conditioners transfer heat, where as most people think it works like a fan blowing over a block of ice.  Think of it as a radiator on a car, which is wind blowing over hot water in tubes transferring the heat, cooling the water.  He told me Earth has natural air conditioners.  Then he asked me why was water always colder at the bottom of waterfalls and the longer the fall, the colder the water

.  The more air exposure it has,  the more heat is transferred.  He has just added a water fall to the system staggering some existing media and adding some large river stone .  The down side, he said, would be evaporation, but it was easier to replace water than fish. We are looking for some high temps here as well. I am logging temps and will post.

[TCLynx]

The dryer the climate, the more effective the evaporation cooling will be.  Out west it tends to be quite effective while here in FL it will be a bit more marginal.

[Linda Sunshine Haynie]

True,  The humidity levels play an important factor, as well as shading.  A 2*-4* change is all you can expect sometimes here in Fl.,but It is a natural factor that can be used, as you said, by our kindred, in less humid climates.